The present invention relates to a folding bicycle.
Numerous bicycle structures exist that enable the bicycle to be folded in such a manner as to reduce the size of the bicycle when not in use and make it easier to stow.
All such bicycles comprise a frame having a front portion on which a steering post is pivotally mounted with a bottom end provided with a first wheel and a top end provided with handlebars, a rear portion on which a second wheel is mounted, and a central portion having mounted thereon a seat and a pedal unit connected to the rear wheel by transmission means.
In the unfolded state, and regardless of the structure of the bicycle in question, the seat, the pedal unit, the steering post, the front wheel, and the rear wheel are all contained in a common plane, and the bicycle presents a wheelbase (i.e. the distance between its front and rear wheels) that is long enough to enable it to provide the stability needed for it to be used as a means of transport.
In contrast, the disposition of the elements constituting the bicycle when in the folded state differs depending on the bicycle structure under consideration.
Documents EP-A-0 323 964 and GB-A-2 021 055 disclose bicycles having wheels that extend substantially side by side when the bicycle is in its folded state. That configuration is advantageous because it is compact. However it requires the frame to present elements that are connected to one another by hinges with axes that are not parallel, such that making the structure of such bicycles is relatively complicated. Folding and deploying the bicycle are not always easy, in particular because of the complexity of the maneuvers that need to be performed. In addition, once the bicycle is folded, it is generally necessary to carry it, and that can be difficult in particular because of the weight of the bicycle.
Document EP-A-0 388 540 discloses a bicycle in which the wheels extend one behind the other when the bicycle is in the folded state. Nevertheless, in that case also, the structure of the bicycle is relatively complex. In addition, given the arrangement of the component parts of the bicycle once it has been folded, the only way of transporting the folded bicycle is to carry it.
Thus, with a folded bicycle of known type, a user entering a pedestrian zone (whether a pedestrianized street or inside covered premises such as a shop) must either push the bicycle in an unfolded state beside the user where, given its length and poor maneuverability, it runs the risk of getting in the way of other pedestrians, particularly in areas that are very crowded, or must leave the bicycle outside the pedestrian area in which case the user runs the risk of having it stolen, or else must fold the bicycle and then carry it in order to access the pedestrian area, in which case the user is hindered in moving about and is likely to tire quickly.
Folding bicycles are also known comprising a frame having a front portion on which a steering post is mounted, the steering post having a bottom end provided with a first wheel and a top end provided with handlebars, a central portion on which a seat and a pedal unit are mounted, and a rear portion which comprises an arm having a first end on which a second wheel is mounted, the second wheel being connected to the pedal unit by transmission means, and an opposite, second end connected to the central portion by a hinge so that the rear wheel is movable between a spaced-apart position and a close-together position relative to the front wheel. Thus, it is possible to reduce the wheelbase of the bicycle while keeping the front and rear wheels in the plane of the bicycle so that the bicycle can still run and be guided by a user pushing it from the side. It is then easier for the user to penetrate into pedestrian areas while pushing the bicycle without hindering other people present in the pedestrian area because of the short wheelbase of the bicycle. Nevertheless, handling and locking the bicycle in its various positions turn out to be relatively complex.
An object of the invention is to propose a folding bicycle of the above type which is simpler in structure, enabling the operations of folding and deploying to be performed easily and quickly.
In order to achieve this object, the folding bicycle comprises a seat secured to a post slidably received in a sheath mounted on the central portion to slide between an in-use position in which the seat is remote from the pedal unit and a shoulder surface of the sheath is in abutment beneath the central portion, and a stowage position in which the seat is adjacent to the pedal unit, and the sheath has means for locking the arm in the spaced-apart position, which means are arranged to cooperate with the second end of the arm and oppose movement of the sheath towards its stowage position when the sheath is in its in-use position.
Handling the sheath enables the wheel to be locked in the spaced-apart position so that locking can be performed simply and quickly. The locking means perform two functions, namely: preventing the rear wheel from moving away from its spaced-apart position; and keeping the sheath in its in-use position, thus providing a structure that is simple. In addition, the use of a sliding sheath for the seat post makes it possible for the bicycle in the folded state to have a structure that is compact.
Preferably, the second end of the arm has an arm abutment surface beyond the hinge for coming into abutment against a corresponding surface of the central portion to define the spaced-apart position of the rear wheel, and the bicycle includes a rod for locking the arm in the spaced-apart position, the locking rod having one end mounted on the sheath to pivot when the sheath is in its in-use position between a locked position in which the opposite end of the locking rod bears against the second end of the arm to press the abutment surface against the corresponding surface of the central portion, and an unlocked position in which the opposite end of the locking rod is retracted relative to the second end of the arm.
While the bicycle is in an unfolded state, the locking rod then performs two functions, namely: locking the arm in the spaced-apart position; and keeping the sheath in the in-use position. The bicycle is folded by retracting the free end of the locking rod so as firstly to release the second end of the arm, thereby allowing it to return to the close-together position, and secondly enabling the sheath to move into the stowage position.
Also advantageously, the locking rod is provided at its end mounted on the sheath with a stop for co-operating with the second end of the arm when the sheath is in its stowage position and the arm is in its close-together position, so as to oppose displacement of the arm towards its spaced-apart position.
It is then particularly simple to lock the arm in its two positions.
In a particular embodiment, the front portion and the central portion of the frame are connected together by a deformable parallelogram having hinges with axes substantially perpendicular to said plane, and the rear portion is mounted on the central portion by a hinge with an axis substantially perpendicular to said plane in such a manner that the wheels are movable relative to each other between a spaced-apart position corresponding to the bicycle being in its unfolded state, and a close-together position beneath the pedal unit corresponding to the bicycle being in a folded state.
The bicycle can then be folded simply and quickly by raising the central portion of the frame so as to cause the wheels to fold under the pedal unit. The structure of the bicycle is also relatively simple.
According to a particular characteristic, the bicycle includes a synchronizing rod for synchronizing the movements of the front and rear portions, the synchronizing rod having one end fixed to the deformable parallelogram, and one end fixed to the second end of the arm.
This simplifies handling by coordinating the movements of the front and rear portions.
According to another particular characteristic, the transmission means include an intermediate pair of chain wheels mounted to rotate about the hinge axis between the rear portion and the central portion of the frame, and connected both to the pedal unit to be driven thereby, and to the rear wheel in order to drive it.
When the transmission is implemented by means of flexible connections such as chains or belts, the use of an intermediate pair of chain wheels, or the like, enables the lengths of the connections to be kept constant and can optionally also serve to obtain a gear ratio that is particularly useful when the bicycle has wheels of small diameter.